Air separator



Nov. 7, 1933. T. J. STURTEVANT AIR SEPARATOR 2 Sheets-Sheet 1 Filed Nov. 25, 1950 INVENTOR 7 i4 BY W W, 2 TORNEY Nov. 7, 1933.

T. J, STURTEVANT AIR 5 EPARATOR 1930 2 Sheets-Sheet 2 Filed Nov. 25

INVENTOR BY %%Mm ATI' RNEY Patented Nov. 7, 1933 AIR SEPARATOR Thomas J. Sturtevant, Wellesley, Mass, assignor 'to Sturtevant Mill Company, Boston, Mass, a

corporation of Massachusetts Application November 25, 1930 Serial No. 498,071

1 Claim.

The invention to be hereinafter described relates to air separators for grading materials. The invention is embodied ina separator of the type in which the classification is accomplished by an air current moving upward 'in a separating chamber and downward in a settling chamber. The air moves in a closed circuit, and in its course passes from the settling chamber through an inlet opening into the separating chamber, and from the separating chamber through an outlet opening into the settling chamber. The air current is induced by a fan which is located adjacent to the outlet opening. The materials to be graded are fed through a hopper into, the separating chamber, and are received by a rotary distributor which throws the materials out across the rising air current under the influence of centrifugal force. The lighter particles are carried upward by the air current through the outlet opening over into the settling chamber where they gravitate downward and are delivered therefrom while the heavier particles or tailings gravitate downward through the rising air current in the separating chamber and are delivered therefrom.

Efficiency oi classification requires that larger particles shall not be carried with the fines from the separating chamber through the outlet opening over into the settling chamber. If a fan is provided in the separating chamber beneath the outlet opening, it is effective in promoting whirl of theair current with a centrifugal effect which throws the heavier particles out toward the wall of the separating chamber and materially reduces the liability of some of them being carried out with the fines. However, such a fan produces a suction down through the outlet opening which must be overcome by the fan above the outlet opening. As a consequence, if it is desired to rotate the fan above the outlet opening at high speed as required for separating some grades of material, an objectionable amount of power is required, increasing the cost of operation and producing T excessive wear on the parts.

A purpose of the pres nt invention, therefore, is to provide a construction in which the whirl of the air current and centrifugal eifect are promoted in the separating chamber beneath the outlet opening, but without materially opposing rotation of the main air circulating fan. In carrying the invention into practical effect, rotary foraminated bailie plates are provided between the distributor plate and the outlet opening, and have classifying zones between themJGal shell 19.

The construction is such that materials may pass from the distributor plate up into said zones, and the air whirled by'and between the plates will develop a centrifugal effect which The character of the invention will. be best understood by reference to the following description of the separator shown in the accompanying drawings, wherein:

Fig. 1 is a vertical section through the air separator;

Fig. 2 is a plan of one of the'baflle plates;

Fig. 3 is a horizontal section taken on line 33 of Fig. 1; I

Fig. 4 is a horizontal section taken on line 4-4 of Fig. 1;'

Fig. 5 is a detail showing one of the vanes that may be used on the upper baffle plate; and

Fig. 6 is a plan of a portion of a modified form of baflle plate. I

Referring to the drawings, the separator shown therein as one good embodiment of the invention, comprises an outer casing 1 consisting of a drum 3 having a head 5 at the top thereof, and a cone '7 at the lower end thereof terminating in a discharge spout 9. Within and spaced from the outer casing is an inner casing 11 consisting of a drum 13'having a head 15 at the top thereof with an outlet opening 17 therein. Projecting down from the'drum is a conical shell 19,

and beneath and spaced therefrom is a conical shell 21 having a discharge spout 23 at the lower end thereof which extends laterally through an opening'in the cone 7. The drum 13 is supported by brackets 25 secured to the drums 3 and 13.

In the inner casing is the separating chamber 2'7, and between the inner and outer casings is the settling chamber 35. The space between the conical shells 19 and 21 servesas an inlet opening for the passage of air from the settling chamber into the separating chamber. Located at this space is a series of vanes 37 (Figs. 1 and 3) having flanges 39 at the upper ends thereof pivotally connected to a ring 41 secured to and projecting outward from the lower edge of the coni- These vanes are adjustable to vary the area of the opening at the inlet, and to accomplish this the flanges carry and are pivotally connected to a ring 43. A red has one end pivotally connected to the ring, and extends through a sleeve bracket 47 secured to the outer casing drum. A hand wheel 49 is mounted on the bracket, and has a hub threaded to the rod confined against movement axially thereof. Rotation of the hand wheel will adjust the rod longitudinally of the bracket, and thereby impart rotative movement to the ring 43, and the latter will rock the vanes on their pivots to vary the spacing between them. These vanes and the means for adjusting the same may be similar to the construction disclosed in Letters Patent No. 1,788,361, granted to me January 6, 1931 To vary the outlet opening 17 in the head of the separating chamber, a valve may be provided comprising a series of overlapped plates 51 (Figs. 1 and 4) resting upon said head and provided with radial bars or handles 53 which extend through guide brackets 55 on the outer casing drum, said handles being accessible extcriorly of said drum for adjusting the plates inward and outward to vary the area of the outlet opening. This valve may be similar to that disclosed in Letters Patent No. 1,615,558, granted to me January 25, 1927.

The materials to be graded are conducted into the separating chamber through an upper hopper 57 (Fig. 1), and thence through a conical hopper 59 secured tothe outer casing head and having a neck 61 extending down through the outlet opening in the separating chamber head.

Mounted on the head of the outer casing are channels 63 supporting a housing 65 having bearings in the upper and lower ends thereof. A vertical shaft 67 is journalled in said bearings, and extends downward through the hopper 59 and beyond the same into the separating chamber. A bevel gear 69 fast on said shaft meshes with a bevel pinion 71 fast on a horizontal shaft 73 journalled in a bearing carried by the housing 65 and in a bearing 75 carried by a transverse channel 77 supported on the channels 63. At the outer end of the shaft 73 is a pulley 79 which may be driven from any suitable source of power. Mounted on the shaft beneath the hopper neck 61 is a rotary distributor 81 having a hub 83 with a plate 85 bolted thereto. Projecting up from the distributor hub are posts87, and secured thereon is the lower flange of a sleeve hub 89 at the'top of which is a flange having arms 91 secured thereto and carrying fan blades 93 located above the outlet opening and in a chamber 95 between the outer and inner'casing heads. This fan serves to develop the air current which whirls and circulates around the fan chamber 95, down through the settling chamber 35, through the inlet opening formed by the spaces between the vanes 37, up through the separating chamber 27 and through the outlet opening 17 in the separating chamber head. The materials to be graded are fed through the hoppers 57 and 59 to the distributor 81, and are thrown outwardly thereby under the influence of centrifugal force toward thewall of the separating chamber, and in so doing they meet the upward whirling air current, the lighter particles being carried through the outlet opening over into the settling chamber, while the heavier particles or tailings, gravitate downward through the rising air current in the separating chamber, the

fines and tailings being discharged respectively through the spouts 9 and 23.

As stated, a purpose of the present invention is to provide means by which the whirl of the air current and centrifugal, effect are promoted in the separating chamber beneath the outlet opening, but without materially opposing rotation of the main aircirculating fan 93. This means, in the present instance comprises a plurality of baffle plates 97, 99 and 101, each formed of sections 103 (Fig. 2), and each section having anouter foraminous portion 105 and an inner solid portion 107. The perforations may be circular as shown in Fig. 2, or some of them may be circular and others may be elongated slots (Fig. 6)' opening at the periphery of the plate. Also, the perforations may be otherwise formed according to conditions as required. It will be understood that the term foraminous in the claims is to be considered as generic to a perforated plate having perforations of any suitable form, and also generic to a woven or screen structure.

The margins of adjacent sections of the plate are overlapped and bolted together. The inner marginal portions of the sections rest upon'the lower flange of the hub 89. The plate 99 is spaced from the plate 97 by a pair of concentric rings 109, and the plate 101 is spaced from the plate 99 by a pair of concentric rings 111. The assembly of plates and rings is secured to the hub flange by 113 which pass through registering holes in the plates, through the spaces between the several pairs of rings, and through holes in the hub flange and a ring at the upper ends of the posts 37 referred to. Preferably the distributor plate 85 is of snail diameter and does not overlap more than half the radius of the bafile plate 97 measured from its inner edge to its outer edge. In other words, it should not cover the foraminous portion of the plate.

In operation, the materials to be graded are fed through the hoppers 57 and 59 to the distributor 81, and under the influence of centrifugal force are thrown outward along the distributor plate 85 toward the wall of the separating chamber. The air whirling and rising in the separating chamber will carry the lighter particles up through the outlet opening through the fan chamber and over into the settling chamber, where they will gravitate down and discharge from the spout 9, while the heavier particles will gravitate down through the. rising air current in the separating chamber and discharge through the spout 23.

The rising air current will pass through the perforations in the baifie plates and carry material with it into the spaces between the plates which are separating zones. If two baffle plates are employed, the materials will pass through the perforations of the lower plate 97, and the lighter particles will pass through the perforations in the plate 99. If three plates are employed, lighter and some heavier particles may pass through the perforations in the plate 99 into the space between the plates 99 and 101, and the lighter particles will pass through the perforations in the plate 101 and be carried on over into the settling chamber. The air and the material carried thereby into the zones between the plates are whirled in said zones, and a centrifugal effect is developed which throws the heavier particles out of said zones'beyond the peripheries of the plates, and they then gravitate downward through the space between the plates and the wall of the separating chamber. These bafile plates are not only highly desirable in promoting eificient classification, but also they produce the whirl and centrifugal effect without opposing materially the rotation of the fan 93. Consequently, the fan may be driven at high speed as required for finer grades of classification and without requiring excessive power, and without objectionable wear on the driven mechanism. When the separator is to be operated in separating coarser grades of material, it is not always necessary that the fan assembly shall be driven at such high speed. For fine work at these lower speeds vanes 115 (Fig. 5). to increase the whirl may be provided on the upper baffle plate 101 and secured by the same bolts which hold the sections of said plate together.

The foraminated portion of series or stack of battle plates, as illustrated, extends outward almost to the wall of the separating chamber and is substantially covered by the cover 15 of said chamber surrounding the central outlet 17. This is important because the dust laden air, after circulating through the area adjacent the wall of the separating chamber and passing through the outer foraminated margin of the baille, has to move inward against centrifugal force in order to pass through the outlet 17, which is protected from short circuiting of the heavy particles therethrough by the impervious inner portion of the baflle. The bafiie plates act to reject the oversize particles and such particles as may pass through the bailie are projected against the overlying separator cover, or at least into the more or less dead air space in the upper corner of the separating chamber. On falling back upon the bafile plate 101 they are swept outward to the separator wall and thence pass downward to the discharge spout 23. Coincident with this action the dust is carried inward by the current of air turned inward over the impervious inner portion of the baiile and seeking an exit through the centralized top opening. Thus the construction of the separating chamber, the construction of the baflle and the relation of the foraminated portion of the baffie to the top opening each modifies the other to increase and make more uniform the centrifugal selective action. Vanes 115 on the bafile plate 101 may be used, as stated, to vary the classifi cation. Variation of classification is secured also by judicious control of the area of the inlet and outlet openings through manipulation of the valves 3'7 and 51, respectively, which, by changing the speed of the circulating current, with the centrifugal force remaining constant, modifies'the action of the baffle on the heavier whirling particles.

This separator may classify materials of varying character, and separate fines of varying sizes. The openings in the bafile plates are of fixed size, but by adjusting the vanes at the inlet opening and the valve at the outlet opening, or either of them, the volume and velocity of the air current circulating through the chambers, plates and openings may be varied, and the classification efiect can be regulated. Since the plates are made of detachably connected sections, and the sections are detachably connected to the distributor plate hub, sections having perforations of various sizes and shapes may be used according to the grade of the product to be separated.

It will be understood that the invention is not limited to the specific embodiment shown, and that various deviations may be made therefrom without departing from the spirit and'scope of the appended claim.

What is claimed is:

An air separator for classifying materials comprising inner and outer covered separating and settling chambers having inlet and outlet open ings between them said outlet opening being centralized in the separating chamber cover and being of considerably less area than the cross sectional area where the cover and opening are located, a fan above the outlet opening for causing air to circulate and whirl through said chambers and openings and move up in the separating chamber and down in the settling chamber, a rotary distributor for delivering materials into the path of the up-moving air in the separating chamber, and a vertical series of rotary partially foraminated bafiie plates between the distributor and outlet opening and mounted to rotate with the distributor said plates each having a marginal portion underlying the annular separating chamber cover and having a separating space between them, said plates being adapted to promote whirl of the air and centrifugal effect opposing the passage of heavier particles through the outlet opening and the uppermost plate having vanes on its top face across the foraminated portion thereof to further promote the whirl of the air. 25

' THOMAS J. STURTEVANT. 

